Combined line finder final selector circuit



Sept. 30, 1952 R." M. M. OBERMAN COMBINED LINE FINDER FINAL SELECTORCIRCUIT Filed July 30, 1947 INVENTOR.

. I \i F CALL DEVICE Patented Sept. 30, i952 UNITED. STATES" Pare} r relcs COMBINED LINE FINDER FINAL I SELECTOR CIRCUIT Itoelo f Oberman,TheHague. Netherlands Applicationfiuly' 30.1947, Serial No. 767,526 I IIn the Netherlands June 5, 1946 Section 1,, Public Law 690, August 8,194s Patent expires June 5, 1966 4 Claims. (Cl. 179'18) 1 The inventionrefers to a' circuit which in a automatic signallingsystem in particulara telegraphor telephone system may perform. the function of call finderand of final selector.

A system of this. nature is e g. known .from the so-called crossbarsystem, in which the apparatus belonging to a subscriber individuallyconsistsonly of a line relay and of a vertical'section of a so-calledcrossbar switch carrying incoming as well .as outgoing traffic, .asecond switching frame making the division between incomingand-outgoingtrafilc,-the entire stage being controlled'by auxiliary apparatus commonto a number of frames ii the finding of acal'lis c'oncerned, Whereas aconnection-to a called subscriber may be established on these frames bya register together with another auxiliarymarking I device, common tothese frames.

' The combination of a call finder and a final se- 1 lector is alsoknown froi n a system for small ter- .minal exchanges-with one selectingstage, which has rotating switches and is positioned forboth functionsby means of a complicated control circult in the exchange directlycoupled to this stage.

The combined' call finder/final selector circuit contains; a relativelygreat number of relays serving only one ofthe two functions. Thecombination of callfinder and'finalselector in large exchanges accordingto this system leads to circuits which are too complicated; trom ,aneconomic standpoint. I I I The system of theiinventiori provides acombined'call finder and final selector circuit which entirely avoidsthe above'difficulties of common control apparatus for this stage in,the exchange concerned, whereas the relays (oneor two) present in thecombined circuit all serve one purcombined can finder/final selectorcircuit which is entirely controlled by the register regardless of theselecting or finding stages between the regis- I t e'r and the combinedcircuit may be 'used to advantage in considerable exchanges as. well" asin {small terminalexcha'n'gesdue to its simplicity.

I The'system of. thein'vention-is obtained by combining a normal finderselector stage and a call finder stage such that the wiper of thecombined call finder/ final selector. essaying the marking for the final,selectonposition, is onlyco'nnectedto apositionof the preceding groupselector; the wiper essaying them'arking for positionin .the switch ascall finder being only connected to a position oi the following callfinder. theremaining switching eme-11 serving in the position of the,switch both when it functions as can finder and as final selector.

The circuit shown in the accompanying draw- ..ing is veryapt for. use incombination with a combined finder/final selector circuit according [totheinvention, as the combinedcircuit requires f our through -,c:.\nductors between the separate call finders and final selectors .e achequipped with fivewipers.

The combination of call finder'and final selector in a single switchhaving the properties of both separate circuitsthus necessitates sixwipers as shown,

1 If the subscriber lifts his receiver from the hook of the set Tslformaking a call a circuit is closed ironi. battery, resistance Wl and W4in series with cell SI, resistance WI, subscribers line, resistance W2,resistance W6 with parallel cell S2 with resistance W5 to ground. Thevolt- I age of point i i which was equal to battery in the condition ofrest of the s ubscriber line changes to a lower negative voltagedepending on the valuesof :said resistances. The shift actuates a call'detector (notsho'wn), which mayin the case of asmall terminal exchangebe situated in the preceding-main exchange. In a manner not shown'in thefigure a free; register is hereby started which finds the call by firstseizing by means of a cord finder a free connecting circuit. 'I hesecond callfinder coupled to I pose as well as the'other, such that onlythe control wire for specifically marking the circuit as f'call finderor asfinal'selector is different The 40 the connecting circuit, is.then' positioned. 'In the-example this is done by means of theequilibrium of D C. Wheatst'one bridges.

other-positioning method in which a register, positions a stageby meansof eithera D. C. or an-A. G. mark ing, is applicableto the inven- Inpn'iicip e the adjustment of-the second can finder is done as follows.The call detector, which may be assigned egg. to 10!} subscribers,

suppliesinformation to the seized register in s va e-id -1 G- volt idicati the hundred .group in which the call is made. I I This DC.voltage should correspond to that determined by potentiometer WQ/Wififrom the combined call finder/final. selector circuit, The ewiperofthesecond callfinder is the control wiper used to test forthe voltagerequired.

If it has been found a free call finder/final selector circuit has beendesignatedhaving access I .to the subscriber hundredgroupin whichthecall' was made. After the second call. finder circuit has beenswitched through theqfirst call finder,

at the-same time selector-circuit, is positioned by "which the callge IN v 7. u H u -ce'iver. After the-busy test the register may-"de wfi g'pm-my of a potentiometer W9/WIO circuit. Contact a2 i'nterrupts thecontrol wiper circuit which was grounded in the register for busyingpurposes-via a low resistance control relay winding. This con trol orsupervisory relay demagnetises, "consequent upon which the zero switchis again connected to the b-wire, now leading 'to'the d=wiper of thecombined call finder/final selector. The e-wire is connected in theregister .to .battery.

thus energising driving magnet K of OZ/EK.

The selector moves till the zero switch finds a voltageon wiping anoutlet which differs from -battery signifying a call. I The callfinder/final selector circuit is thenswitch'ed through; by: re-

moving ground from' the registenc-wireso that relay B may operate inseries with-relay A. Relay '3 contacts connect the necessary wiresto theregister. Before doing this it ispossible to determine the nature of thecalling subscriber in the register by evaluating resistance W4. Thecalling condition of the line circuit is neutralised in switchingthrough the call finder/final" selector circuit by applying battery to'X via contact b4 and small resistance W12.

It is observed that resistance 'WH is'high e. g. 5.10 "ohms. The onlypurpose of this resistance is to provide a slight load on the cells inthe [blocking direction as the cells S'l and'SZ which seldom functionwill not have a 'sufficient blocking resistance within sufficientlyshort time under certain conditions, i v

A connection to a subscriberconnected to a combined call finder/lineselector is made via a 40' g'r'oup's'elector. The control markingpotentiometeriWS/Wlfl) is the same for the positioning of thegroup'selector as for positioning the second call"-finder. The contactsof all' group selector the two b-rows are interconnected. J

' After the positioning of the group selector-the rows and of thesecond'call finder rows'except control ,wire is connected via the b-wiper-of this selector to the f -wiper of the combined call thesubscribed selector, while subsequently this wiper wipes asecondseries'of potentials forposi- 55 firstlinefinder an'das a finalselector and includ 'tioning according to' the "last digit. Bothpositiorii'n'gs' may' be 'efl'ected in the example by means 4 of D. C.Wheatstone bridge equilibria.

The J- wiper wipes in finding'these positions a'niir nber of voltages,e. g. from-battery by means-of a twenty resistances potentiometer,furnishing the After positioning the final selector by the tens and bythe last digit the' register'carries out the busy 'tes't of the calledsubscriber on the c-wirei [If the 'sub'scriber'is' free this is-marked'by ground on thee-contact, if'the line is busytlie'c-contact carriesnegative mage fromfthe fm'oment in ubscr'iber has lifted' his-"re- 25main exchange.

termine the nature of the called subscriber by determining resistance Was in Netherlands Patent applicatoin 120,969.

The combined call finder/final selector circuit is switched through by.removing ground from the register a-wire, whereby the B relay" operatesin series with the A relay. Both relays are held via the d-wiper of thegroup selector and closed contact a in the group selector circuit.

10f Contact b4 connects .battery to point X in the line circuit, wherebythe subscriber line is made symmetrical. Lifting the receiver on anincoming call now does not actuate the call de- "tector.

The call finder/final selector circuit of the :fig'ure may also be usedin a small terminal exchange. Per circuit three wire pairs are thenrequired for connection to the main exchange, all possible facilitiesbeing retained. The re- 20 sistancepotentiometers, of which resistancesW1 and 'W8 are shown should be fed, by means of a wirep a-ir 'occurringonly once per terminal exchange, from the main exchange. The 'wire tothe call detector should also be-prolongedto the In this manner it ispossible to assimilate small terminal exchanges in a main exchangesystem, no registers or tube circuits being required-inthese exchanges,whereby they are reduced to extreme-simplicity.

'It-is also observed that-'the circuit is such that theconnectingcircuit always has access to the registermeter of the subscriber eithercalled or calling. For localcalls it is easily possible to transferthemetering impulse from the calling to the calledsubscriber.

While I have illustrated and described'what I regard to be thepreferredembodiment of my invention, nevertheless it will be understoodthat such is-m'ere'ly exemplary and that numerous modifications andrearrangements may be made therein without departing from the essence'ofthe "inventionflclaim: '"'li An"automatic-transmission system havingselecting" and finding switches, comprising in combin'ation,-a groupselector including a plurality-'of*-banks each having aplurality-ofcontacts; a secondjline finder including a'plurality of banks-eachhaving a pluralityof contacts, said contacts of each bank exc'ept one ofsaid group "fin e e e r this wiper twipi' 'i 'so selector beinginterconnected, respectivelyjwith known manner a series of potentials,by which 'jthe final selector contacts are characteriz ed for anadjustment corresponding toth'e tens 'digit'of said contacts of eachbank except one of said sec- "ond line finder, 'on'e of'saidinterconnected*con "tact banks being'ground'ed when a call is made; aswitch adapted to 'actinany'of the capacities as a fing aplurality of"banks; of contacts and'wipers engaging said tbanksfrespectively; afirst relay connected to said one of 'sa'idiinterconnected con- 'ta'ctsin one ofisaidbanks of said groupselector ands'aitl f second line finderso as to be energized "uponthegrounding thereof,'sai'd first relay hav-*in'gan armature connecting one of said'wip'ers o f said switch'to the'COIlta'CtS'ZOf said bank of said ;groups'elector which are noftinterconnected with 05 "any, "contact: "of TSal'd banks; of said"second' line finde and another armature connecting another 'on'e'o said'wip'ers'j of" said'switch to the ,contacts of'said ba'nkoflsaid'secondjline finder which are not lnterconnectedwith anycontacto'f said banks I of'said'groupselector: a "second relay connectedn in series to said first relay and operated upon re- A fmoving theground from "said' one of the'interconnected contacts-of "said' -one"ofsaid banks of "said fgro'up 'selectonand said second "line "finder;matures actuated by said second relay and connecting, respectively, atleast a further one of said wipers of said switch to-the contacts "ofatleast' one of said contact banks of said group selector 'which areinterconnected, respectively, with saidcontacts of said banks of said 1second line "finder, whereby'in 'the event of a call being made, saidinterconnected contacts in said one" of said banks of said groupselector and said second line'finder are grounded andsaid first relay isenergized thereby actuating said? arma-- tures 'th'jereof and connectingsaid other one of said wipers of said 's'witch'to the contacts of saidbanks of said second line finder which'are not; interconnected with any"contacts of said group-selector, andysaid'one'wiperof said switch to thecontacts oi 'saidgroup selector which are not interconnected with any Icontacts ofi'said second lineflnder, and thenthe ground is removed fromsaid one, of the interconnected conf tacts' off said group selector andsaid second line finder" so that said second relay operates and actuatessaid armatures thereof connecting' at least said further oneofsaidwipers of said switch to the contacts of at least one of said,contact banks of said second' line finder interconnected with thecontacts 'of a bank of said group selector. I. 12, automatictransmission system having selecting 'andfinding switches positionedunder controlof a voltage discriminator arranged in a register andcomparing marking potentials with control'rpotentials'. comprising incombinatioi'na 'g'i'roiipselector including a plurality of'banks eachhaving a plurality of contacts; a second line find?- erflincluding aplurality of banks each havinga plurality of contacts, said cont'acts of,each'bank I except one of said group selector beinginterconf nected;respectively, with said c'ontacts'of each Y bank except one of saidsecond line finder, one of said interconnected contact banks, beinggrounded vvheii'a call is made; a'switch adapted to "act in any of thecapacities as a first line finder and as a final selector and including'a p'lu-" rality of banks of contacts and .wipers' engaging 'said banks,respectively; means for imjpartinga'. control potential to one of saidcontact; banks of said switch; a'firstflrelay connected to 'sjaid'oneofsaid interconnected contacts in (meet said banks of .said group selectorand said second line finder so as to be energized upon'a "groundingthereof, said first relay having an armature connectin said wiperengaging said.

' contact bank of said switch to which isimparted 'theffcontrolpotential to the contacts of said bankof'said group selector which arenot interconnected with any contact of saidbanks' of said seicond'linefinder, and another armature con- -necting another one of said wipersofsaid switch to'the contacts of said bank of'said second line finderwhich are not interconnected with any contact of said' banks of saidgroup selector; a s'econd'relay connected in series to said firstFre'layand operated upon removing the ground fromjfsaidffone of theinterconnected contacts or said one ofsaid banks of saidgroupselectorjandsaid second line finder; and a plurality of farmaturesactuated by's'aid second relay and connecting, respectively, at least afurther one of said wipers of said switch'ito the contacts pil'at least"one of said contact banks of said lg'roup' selector which areinterconnected, respectivelygl with, said. contacts oi said banks ofsaid second line finder, whereby in theevent of a callbeingmade, saidinterconnected con- 6. tacts in said one of said banks-of'said group selector-a'nd saidsecond line finderare grounded and said-firstrelay isenergizedvtherebyactuating'saidarmatures thereof and connecting saidotherone'of said wipers or said switch to the contacts of said banks ofsaid second line'finder whichfare not interconnected with any contactsof said group selector, and saidone wiper of said switch "to thecontacts of said group selector which are not interconnected with anycontacts of said second line finder, and then' the ground is removedfrom said one *of the interconnected contactsof said group selector andsaid second line finder so that said second relay operates andactuates'said armatures thereof connecting at least saidfurther one ofsaid wipers of said switch to the contacts of at least one I of saidcontact banks of said second line finder interconnected with thecontacts'of a bank of said groupselector. I 7 3; An automatictransmission system having selectings and finding switches positionedunder control of a voltage discriminator arranged in a register andcomparing marking potentials with control potentials, comprising incombination,-a line circuit including points each having differentpotentials when saidline circuit is free and engaged, respectively; agroup selector including a plurality of banks each having a plurality ofcontacts; a second line finder ineluding a plurality of banks eachhaving a pluralityof contacts, said contacts of each bank except one ofsaid group'selector being interconnectedg-respectively, with saidcontacts of each bankexcept oneof said second line finder, one ofsaidinterconnected contact banks being grounded when acall-is made; a switchadapted toiact in any of the capacities as a first line finder and as afinal selector and including a plurality of banks of contacts and wipersengaging said banks, respectively; means for imparting ac'ontrolpotential to one of said contact banks of said switch; a'first relayconnected to said one of said interconnected contacts inione of saidbanks of saidgroup selector andsaid second line finder so as to beenergized 'uponla' grounding thereof, said first relay having ,anarmature connecting said wiper engaging said contact; bank of saidswitch which is imparted the control potential to the contacts of saidbank of said group selectorwhich are not interconnected with anyjcontactof said banks of said second line finder, and another armatureconnecting another one of said wipers of said switch to' the'contactsoisaid bankof said second line finder which are not interconnected.

with any contact of said banks of said group selector; means forconnecting saidcontact bank of said switch being ineng'agement with athird one of "said wipers of said switchjto one of the points of'saidllne circuit having different potentials when said line circuitis'free and engaged, respectively; a second relay connected in series to"said first relay and operated upon removing the'ground from said one ofthe interconnected contacts of said one of said banks of "said groupselector and said second'line finder;

and'a plurality of armatures actuated by said second relay andconnecting,respectively, at

least oneof said wipers of said switch tothe "contactsofja't least oneof said contact banks of saidgroup selector-which are interconnected,

respectively, with said contacts 'of said banks offsaid second linefinder, whereby in the event of' a callbeing'made, said interconnectedconsaid second line finder, said fourth armature of said second relayrestoring the potential of a third one of said points of said linefinder circuit connected to said fourth contact bank of said combinedfinal selector and first line finder switch upon energization of saidsecond relay, said fifth armature of said second relay connecting saidfifth wiper of said combined final selector and first line finder switchto said interconnected fifth contact banks of said group se lector andsecond line finder so as to enable the call to be counted, said sixtharmature of said second relay being connected in series with saidcontrol potential imparting means and rendering the same inoperativeupon energization of said second relay, whereby said second wiper ofsaid combined final selector and first line finder switch is connectedby means of said second armature of said second relay to the secondcontact bank of said group selector and by said third armature of saidsecond relay to said secand contact bank of said second line finder.

ROELOF M. M. OBERMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

